TC18钛合金锻棒的方形偏析显微特征

Characterization of Square Segregation in TC18 Titanium Forged Bar

选择TC18钛合金锻棒中的正常区域和方形偏析区域作为研究对象,使用EBSD技术对其显微特征进行定量表征。结果表明,两者组织形态构成相同,但受Fe和Cr元素偏析影响,方形偏析区域相变点更低,更有利于α相析出和形核,因此α相含量更高;此外,两者区域中的α相集中分布在0~40μm^2区间,在温降过程中方形偏析区域速度更慢,因此0~10μm^2面积内的小颗粒α相粒子含量明显高于正常区域并且球化率更高,这表明该锻棒不适合作为转动件长期使用。

Normal and square segregation area of TC18 titanium forged bar were analyzed.EBSD analysis was employed to quantitatively characterize the micro features of both area.The results indicate that the microstructure constitution is similar.However,due to the influence of Fe and Cr segregation,theβtransus temperature is decreased which is benefits for the precipitation and nucleation ofαphase.Consequently the overallαphase content is higher.Besides,αphase is distributed intensely from 0 to 40μm^2.The cooling rate of square segregation area is higher than normal area,thus the 0-10μm^2 smallαparticle is obviously higher than normal area with a higher globularization ratio.The results show that forged TC18 bar is not qulified as rotating part for long-term use.